Glazing-Bead (Portray) Pleated Blind
Glazing-bead (portray) pleated blind installation — the rail seats into the bead inner channel. Bead measurement and edge tightness.
What Is a Glazing Bead (Portray)?
The portray is the channel on the inner face of the bead holding the glass. In some joinery series this channel exists as standard and is designed for the blind rail to seat inside. When the rail settles into this channel the blind looks almost one piece with the window.
The portray channel is a PVC joinery feature but its depth changes by manufacturer. On common joinery brands the channel measurement is standardised. On local or old joinery the channel may be narrow or shallow. On aluminium and timber joinery there is no channel. On these materials the hooked or adhesive mounting gives the same drill-free result.
Not every joinery has a portray channel. On flat-beaded joinery this form is not applied. The channel's existence and measurement change by the joinery series. For this reason in portray mounting the first step is checking the bead section.
How Is the Bead Measurement Checked?
Three measurements are decisive for the rail that will sit in the portray channel.
| Measurement | Why It Matters | How It Is Taken |
|---|---|---|
| Channel depth | The depth the rail will recess | It is measured from the bead inner face to the channel base. |
| Channel width | The opening the rail will fit | It is measured between the channel's two inner walls. If narrow the rail does not enter. |
| Glass–channel share | So the fabric does not rub the glass | The gap between the channel and the glass surface is looked at. |
Where Portray Mounting Makes a Difference
Integrated look
The rail connects to the joinery from inside, not from outside. The blind stands like part of the window design.
Full fit with the sash
The blind stays on the same plane as the glass. No sagging or rubbing while the sash opens and closes.
Least edge light leakage
Since the rail is recessed into the bead channel, the light escape from the sides descends to the lowest level.
The skylight's natural choice
On Velux-type roof windows the portray channel is standard. This mounting is the natural choice there.
Why Does Edge Tightness Come Up?
On a blind the light escape comes not from the fabric but from the edge gaps. Since the portray rail reduces the gap between glass and frame to the least, it makes a meaningful difference especially in rooms wanting blackout. It is the preference reason in bedrooms and presentation areas.
By the same logic it also provides a small contribution in heat passage. As the fabric-edge gap narrows, the airflow between the glass surface and the room decreases.
What Must Be Known While Seating the Portray
The rail is pushed into the channel in a single move at a right angle. A rail pushed at a tilt catches the channel edge and scratches the bead surface. By pushing with equal pressure from the rail ends a click is heard. This sound reports the rail seated into the seat.
On removal the rail's taking out of the channel is also done in a single movement but it is not pulled diagonally. It is pulled with equal force from the rail ends. A rail pulled from one end strains the channel and may leave a mark on the bead.
The portray surface's cleanliness affects the seating. Dust and silicone residue inside the channel prevents the rail's full seating. Wiping the channel with a dry cloth before mounting is the single preparation step.
On some joinery the gasket thickness on the bead differs. The gasket share changes the rail's seating depth into the channel. On joinery where the rail does not seat fully the gasket fit is checked and if needed a different rail profile is produced.
Questions About Glazing-Bead (Portray) Pleated Blind
Does every joinery have a portray channel?
Does a portray blind move together with the sash?
Does portray mounting harm the bead?
Related pages: Hook-Mounted Pleated Blind · Adhesive Pleated Blind · Pleated Blind Systems
Show the Bead Section
A photo of the joinery bead's side section clarifies the portray suitability instantly.
